Using data from a longitudinal study of preterms and full-terms, the present study examined the structure of infant cognition at 12 months, the extent to which five 12-month abilities (attention, processing speed, recognition, recall, and representational competence) mediated the relation from prematurity to mental development at 2-3 years, and how continuity and change in infant information processing from 7 to 12 months affected later outcome. The results indicated that 12-month measures of infant information processing completely mediated the effect of prematurity on outcome and the infant measures form a 'cognitive cascade', similar to that seen at 7 months, in which the two more elementary abilities (attention and speed) influenced the more complex ones, which in turn influenced later cognition. Additionally, despite cross-age stability, 7-month assessments contribute to outcome independently of their 12-month counterparts, suggesting that infant abilities undergo important developmental transformations in the second half of the first year of life.